(within the H.F. amateur bands.)
This is a
brief introduction to receiving
QRSS signals within the H.F. amateur bands based on my own
experiences. The following text assumes the reader is already familiar
with the theory of QRSS. If this is not the case then please have a
look at What is QRSS?
and the links contained within that page. After
reading the theory and explanation of QRSS operation the
following text should make more sense.
need to receive QRSS?
four items are required for the successful reception of
1) A suitable radio receiver.
2) A computer (P.C.) fitted with
a sound card and capable of accepting audio signals from the receiver.
3) Suitable software to process the receivers audio and display the
results on the P.C.s monitor.
4) Some knowledge of where to look in order to have
a good chance of finding QRSS signals.
Choosing a receiver.
the requirements for a QRSS receiver are much the same as for
any other amateur bands receiver, good selectivity, good frequency
stability and reasonable sensitivity consistent with good strong signal
handling capability. However, what may prove to be a
for more general amateur or short wave listener activities may prove to
be very poor for QRSS applications. It is equally true that a simple
home-brew receiver which may not be very good for general amateur use
can prove highly successful for QRSS applications.
results when receiving
QRSS signals perhaps the most important
requirement is that the receiver should have good short/long term
frequency stability. But what happens if the frequency stability is not
as good as it should be? To answer that question let us assume for a
that you have set-up your P.C. with suitable software (more on that
later) and connected the P.C. sound-card I/P to your receiver. Let us
further assume you have tuned your receiver to the correct frequency
and that you have found some QRSS signals to display. If your receiver
does not have satisfactory frequency stability you may find the results
very unsatisfactory. I can demonstrate the results of poor frequency
stability using screen captures taken from Argo
software running on my own P.C. Below are two images showing the result
of poor LO/BFO stability within a receiver.
how the QRSS signal appears to be going "downhill" in the above images
due to the local oscillator and/or the BFO/carrier insertion oscillator
frequency "drifting" with time. The image (above left) shows
the level of drift soon after the receiver had been switched-on, the
second image (above right) shows how the drift begins to reduce (less
sloping of the signal) as the receivers internal temperature
stabilizes. So, the gradient of the "slope" is directly
related to the amount of LO/BFO drift in the receiver. The LO/BFO
frequency drift causes the spectrum of audio frequencies presented to
the P.C. to change in frequency with the result that the processed
signals displayed on the P.C. monitor also appear to change in
over time. If the receiver LO/BFO drift becomes excessive then the
signal will eventually drift outside of the display window requiring
re-tuning of the receiver or adjustment of the display window to
compensate for the error. Also in the first image (above left) notice
the sudden jump in frequency (arrowed) which causes some distortion of
the signals image. So, good frequency stability is a prime requirement
for good QRSS reception.
is worth pointing out that while the receiver used in the examples
above clearly gives less than optimum results for QRSS applications it
has always performed well in general SWL and amateur service, I have
listened to long CW/SSB contacts many times with little or no
re-tuning required. The point is that it would be wrong to
that a receiver which gives satisfactory results in general amateur
service will give equally satisfactory results when used for
term L.O./B.F.O. stability.
from the requirement for long term frequency stability there it is also
desirable that the receiver exhibits good short term frequency
stability. Poor short term frequency stability or "jitter" in the
LO/BFO of the receiver causes the displayed signals to exhibit "wobbly"
or "staggered" lines, this can be seen in the images above in which the
receiver has both poor short and long term frequency stability.
Possible causes of
poor short term stability include poor mechanical construction or
excessive phase noise in
the LO/BFO due to poor design. The "jitter" in the
LO/BFO causes the audio output spectrum from the receiver to be equally
jittery such that the audio signals presented to the PC sound card are
jumping around in frequency. Following processing by the software
this results in a "staggered" or distorted display on the PC
monitor. In extreme cases of LO/BFO phase noise/jitter the signal can
appear to be spread over a wider spectrum of frequencies than it
actually is. This "spreading" of the signal also makes weak signal
recovery less successful.
comparison purposes I have included a screen capture (below)
of a signal received using an old Yaesu FT707 receiver which
incorporates a VFO Because of the less than optimal stability of the
VFO the resulting image of the QRSS signal displays the same "downhill"
slope as the previous examples. What makes this example different is
that the old FT707 has a much better VFO/LO/BFO performance than the
receiver in the previous examples exhibiting much lower phase
noise/jitter. The result is that while the displayed signal is sloping
downhill due to the poor long term frequency stability the signal image
is free of the "stagger" which was visible in the previous examples.
of the simplest ways to improve the long term frequency stability of a
receiver is to ensure good thermal stability of all the oscillators
used in the receiver, this can be accomplished with the use of an
"oven" to regulate and maintain the temperature of the oscillator
circuits or frequency determining components within the
oscillators. More on the subject of temperature stabilization of
oscillators can be found here. Crystal
ovens for QRSS
the receiver you
choose for QRSS reception does not have a temperature stabilized
L.O./B.F.O. it may still give acceptable results if it is left to
"warm-up" long enough such that the receivers internal temperature can
stabilize. The Target HF3S I used for some of the example images shown
above has acceptable frequency stability for QRSS reception if it is
left to warm-up for about six hours! I found it also helps to keep the
shack door closed as well in order to keep the room temperature
Generally AGC is a bad thing when it comes to QRSS reception,
the reason for this is that quite frequently the wanted signal (QRSS)
is very weak and probably just above the noise floor of the system. The
receiver will (even in its narrow bandwidth setting) have an
I.F./A.F. bandwidth of perhaps a few hundred Hz with the result
that stronger signals within the I.F./A.F. pass band may cause
the AGC to reduce the receiver gain. This reduction in receiver gain
not only reduces the strength of the unwanted signal but also the
strength of all signals within the pass band, this in turn can have an
adverse effect on the displayed QRSS signal. The effect of the
stronger unwanted signal which caused the AGC action on the
weaker QRSS signal is sometimes called AGC "pumping" and has the effect
of amplitude modulating the weaker signal. Since the amplitude of a
QRSS signal is normally displayed as a change of display
intensity by the software the net result is that lighter and darker
areas appear on the displayed images which correspond to the AGC action
on the stronger signal. This effect can be seen in the two images shown
below where the FSK-CW signal "fades" due to the action of the AGC,
notice the Morse character "F" (left hand image below) has faded and
part of the "M" pattern has also faded due to AGC action. The QRM
signal used for the examples below was a locally generated CW signal
with the "key down" every few seconds.
undesirable "feature" of some receivers is the effect of distortion
(I.M.D.) within the audio stages of the receiver. In normal amateur
radio service the audio stages can have several percent of distortion
and the effects often go unnoticed since they have little or no effect
on the intelligibility of narrow bandwidth telephony (speech) or
telegraphy (CW) but with QRSS those unwanted IMD products can manifest
themselves as unwanted "ghost" signals when viewed on the PC running
QRSS software. The image on the right (above) shows the effect of AGC
"pumping" and also shows some of the IMD products caused by the strong
signal used to induce the AGC action, the unwanted "ghost" signals are
for best results when receiving QRSS use a narrow I.F. bandwidth
setting and make sure the AGC is turned off. Reduced BW will help to
reduce the effects off unwanted signals and improve QRSS reception.
Since the QRSS sub-bands are generally no more than 100 Hz wide it is
quite acceptable to use a BW of say 300 to 500 Hz as might be used in
CW operation. If your chosen receiver does not have such narrow
bandwidth settings you may still be able to obtain acceptable results
with QRSS though much depends on the level of band activity and just
how strong the QRM signals are.
to sum up, here are some of the desirable qualities for a good QRSS
receiver which are additional to the requirements for regular amateur
Exceptionally good long term frequency stability.
Good short term frequency stability (No "jitter" in the LO/BFO etc)
Good sensitivity consistent with good dynamic range.
No AGC or AGC switched-off.
Low IMD in the audio stages.
6) A choice of I.F. bandwidths
with at least one CW bandwidth setting of 500 Hz or
If after reading these
notes you decide that nothing you currently have in your shack is
suitable for QRSS reception then you may wish to consider home brewing
a receiver. As indicated earlier, successful receivers for QRSS
reception need not be complex and can be built using readily available
An example of a
simple home brew direct conversion receiver for 30 Mtr QRSS reception
can be found here.
A simple 30 Mtr direct conversion
receiver for QRSS reception.
Here are two example images of several QRSS signals obtained
simple (but very stable) direct conversion receiver mentioned above.
many cases the choice of antenna that will be used is dictated by an
individuals QTH, personal preference, local restrictions or the space
available for antennas. My preference for any receiving
antenna is to have some form of "balanced" antenna such as a
my QTH local noise/QRM is a dominant feature on all of the
up to about 22 MHz and I have found that the use of a balanced
receiving antenna helps to reduce the local QRM considerably. If you
happen to live in an electrically "quiet" QTH then an antenna which
"captures" as much of the signal as possible may be your preference,
you may even prefer to use a vertical antenna with a view to picking up
more of the low angle radiation.
you are new to QRSS and currently have no antenna for the 30 Mtr band
then I would recommend a trusty dipole as a good starting point. Mount
the dipole as high as you can and if possible keep it as far away from
any known local QRM sources such as TV sets, Computers etc. Use a
balanced feeder all the way back to the shack or a balun at the dipole
center with a good quality
coax feeder back to the shack. A very interesting design for a compact
30 Mtr dipole appears on the web pages of I2NDT (Claudio), this antenna
is suitable for both RX and TX purposes. A link to his page appears
Dipole Antenna design by Claudio (I2NDT)
you are troubled by local noise then you could try a small
antenna. I use an active loop antenna here and have found it to be very
successful at defeating local QRM. Several choices are possible, a
passive resonant loop antenna which has a high "Q" and narrow BW, this
helps to reduce the level out-of-band signals and helps to prevent IMD
in the front end of the receiver which can arise from powerful SW BC
stations. Even low levels of IMD can cause "ghost" signals to appear
which can be mistaken for QRSS carriers. Another form of loop antenna
is the compact "active loop" antenna, the "active" part is an RF
pre-amplifier which is used to compensate for the small dimensions of
the receiving loop. A compact active loop can also be made resonant and
of its small physical size it needs less space than other forms of
antenna. A variation on the resonant active loop is the broad-band
active loop, this is also a "balanced" antenna and
therefore resistant to local QRM but has the added advantage of being
able to cover the entire L.F./H.F. spectrum. This is good if you have
limited space for antennas and wish to pursue QRSS and general SWL
activities. This has been the case here at M0AYF where a broad-band
active loop has been used for a couple of years now with good results. The
possible disadvantage of the broad band active loop is that it
risks IMD in the front end of the receiver due to the high strength of
signals which are far removed from the frequency of interest. IMD has
not been a problem here at M0AYF and if your
chosen receiver has good IMD performance then the broad band loop may
be a choice worth consideration. The physical location of the loop (be
active/passive/resonant or non-resonant) should be chosen with the same
considerations as for the dipole mentioned earlier. If you are
interested in experimenting with a "wide bandwidth active loop
antenna" then follow the link below.
A Wide Bandwidth
Active Loop Receiving Antenna.
pieces of software exist which are suitable for viewing QRSS signals
but since this web page is intended for those with no prior experience
of QRSS I will describe the use of just one such software package.
If you have never looked for
QRSS signals before and you are completely new to QRSS then my advice
would be to begin by downloading a copy of Argo
can be downloaded from the web pages of I2PHD using the link below.
to Argo web site.
First read the instructions for that software to become familiar with
its operation. Argo
is well written and very easy to use, connection to the radio receiver
is via the P.C. sound cards "Line I/P" the same as many of the other
sound card based software packages currently available. For more
information and advice on
connecting your P.C. to your receiver have a look at these web
Having connected your radio receiver to your P.C.s sound card you
should now check that the P.C. is getting the audio signal from your
receiver. This can be done in several ways but perhaps the easiest
method is to "loop through" the sound card and check you can hear the
sound from your radio receiver also coming out of your P.C.'s
speakers. The sound should be set to a reasonable level such that it is
loud enough to be heard but not distorted. Having confirmed that the
receivers sound is reaching the P.C. correctly you can now attempt to
tune in a test signal with which to check the operation of Argo
Look for a weak broadcast station carrier or
other stable signal
that is weak but constant and set the receiver so you get an audio
note" with a pitch of around 800 Hz. Now launch Argo
and using Argo's "Full Band View" you should see a vertical white line
(or thick white bar) running vertically down the screen at around 800
Hz. You should find that by adjusting the clarifier control the pitch
of the "beat note" changes and the position of the white
also changes. This will indicate that the receiver/P.C. sound card
connections are correct. If you have problems then re-check the
connections to your receiver/P.C. sound card and/or consult the
instruction manuals for your P.C./Sound card and receiver.
you don't know exactly where to look for QRSS signals then its like
"looking for a needle in a haystack" so if your new to QRSS I would
suggest looking around 10.140 MHz but before you do so please check the
calibration of your receiver. The indicated frequency on the receivers
frequency display is no proof that it is the true frequency
being received. An error of only 100 Hz could mean the difference
between successful reception of QRSS or not seeing anything at all. An
error of +/- 100 Hz may be fully acceptable for CW/SSB
working but for QRSS
reception an error of +/- 10 Hz would be more acceptable. To
check your receivers frequency display accuracy you can
use one of the methods listed below for calibration.
1) One of the many frequency standard broadcasts (MSF on 60 kHz, WWV on
10 MHz etc)
2) A GPS disciplined
3) Use an existing QRSS
signal of known accuracy as a comparative reference.
4) Take the horizontal
synchronizing pulses from a TV broadcast and use them to phase lock a
crystal reference oscillator.
5) Use one of the "Propagation Beacons" for frequency calibration. (Beware of this
1) One of the many frequency standard broadcasts (MSF on 60 kHz or WWV
on 10 MHz)
The short list of
options above are
intended only as a guide, you may prefer to use a different option. My
own current preference is to use a harmonic of a 10 kHz square
wave signal derived from a divided down 6 MHz crystal oscillator which
is phase locked to MSF on 60 kHz. The design I use is based on a design
built by Andy (G4OEP) which can be found here. MSF "Off-Air" Standard.
version of the MSF phase locked reference can be found here.
An MSF Locked Frequency Standard for QRSS Calibration.
2) A GPS disciplined crystal
option above is becoming increasingly popular due to the falling cost
and availability of GPS systems. Many of the units available provide an
O/P which is phase locked to the atomic clocks used in the GPS
satellites. More information on this option can be found here.
GPS Disciplined Oscillator.
3) Use an existing QRSS signal of
known accuracy as a comparative reference.
Of the four possible
above number three is perhaps the simplest but you have to be sure that
the QRSS signal you choose has a known frequency and is very stable.
4) Take the horizontal
synchronizing pulses from a TV broadcast and use them to phase lock a
crystal reference oscillator.
The line timebase synchronizing pulses for analog television
broadcasting are generally derived from a very stable source so by
phase locking a crystal oscillator to these pulses it is possible to
make a very accurate and stable reference source for frequency
calibration. The signal can be taken from the composite video O/P of a
SCART connector or the phono (RCA socket) composite video O/P found on
the back of some TV sets. A word of caution, it seems that with the
move towards digital broadcasting you may find that the composite video
O/P of a digital TV receiver/decoder has some "irregularities" in the
recovered synchronizing pulses which make it unsuitable for frequency
calibration purposes. You would have to check the technical details of
the chosen broadcaster before building a unit based on the use of
synchronizing pulses. Here in the UK we still have analog TV
broadcasting and the BBC transmissions use synchronizing pulses which
are locked to an atomic standard so they would be entirely suitable as
a reference for calibration purposes. However, over the next few years
the move towards "all digital" TV means that synchronizing pulses
derived from an all digital system may not be suitable for calibration
5) Use of
"Propagation Beacons" for frequency calibration (Beware of this method!).
Before we go any
cautionary note. In my own early experiments with QRSS viewing I had
been using the IK3NWX propagation beacon on 10.1418 MHz as a frequency
calibration source. The receiver I was using at the time was a Target
HF3S, this is the same receiver used for the examples of a poor
frequency stability receiver shown above. Because of the wide I.F. B.W.
of the receiver (around 4 kHz or more) I was able to see the IK3NWX
beacon using Argo
in "Full BW" mode while simultaneously being able to see the QRSS
sub-band. By adjusting the receiver BFO such that IK3NWX appeared at
around 2.5 kHz in Argo
would then know to look for QRSS between 700 and 800 Hz which equates
to 10.140000 - 10.140100 MHz. This worked quite well but on some
occasions it was evident that I was "missing" part of the QRSS band. It
turned out that it was the IK3NWX beacon which had "drifted" very
slightly in frequency. So, if you choose a propagation beacon
for frequency calibration then first check up on its frequency
stability. It is only fair to point out that the IK3NWX propagation
beacon does not drift very much and by most standards actually has
excellent frequency stability. The very slight changes in frequency of
the beacon only become apparent when compared
to other more
stable frequency sources. If you are in the EU then using the
IK3NWX propagation beacon
would help to put you in the right "ball park" for QRSS viewing in the
absence of one of the other frequency calibration methods listed
above. I should also like to add that the IK3NWX propagation
beacon is an excellent indication of propagation conditions and at this
location (IO93oj) it has proved to be a very accurate indicator for the
possibility of receiving EU QRSS signals at any given time. I have
found that if IK3NWX is weak but detectable in Argo then it
is fair to assume that
other EU QRSS signals will be detectable here in the UK.
Probably 90% of the QRSS activity takes
place in the 30 Mtr amateur band between 10.140000 and 10.140100 MHz
(100 Hz window), this is not an "official"
sub-band, it simply happens
to be where most of the QRSS activity takes place. The propagation
conditions on this band are such that contacts from just a few hundred
kilometers to thousands of kilometers are possible even with modest
and low power levels. Activity also takes place (to a lesser extent)
in the 40, 80 and 160 Mtr bands. The exact frequencies are often linked
to readily available crystals, for example QRSS signals in the 80 Mtr
band are often located around 3.580 MHz and in the 40 Mtr band 7 MHz
crystals are often used so the signal can be located within the first
100 Hz or so just above 7 MHz. There has also been activity
within the 10 Mtr band using very low power (a few mW) from "canned"
modules. There are no fixed rules on the exact frequency or bands used
QRSS but given the nature of QRSS it makes sense to co-ordinate
activity as much as possible with other enthusiasts in order to have
the best chance of receiving other peoples signals or having your own
received by others. To that end there is a very active mailing
the Internet dedicated to QRSS activity which can be found here.
subscribing to the QRSS mailing list can be found here.
In addition to the QRSS
mailing list there is also a QRSS "clip-board" which details some
not all) of the current QRSS activity at any given time, both of these
resources can be
very useful in identifying QRSS signals. The QRSS clip-board can be
More QRSS related
resources can be found on my links page here.
number of QRSS enthusiasts
have HF receivers connected to a PC uploading real-time screen captures
of qrss signals to
the web. Since both the number and status of these on-line resources
may vary IK0VVE
has created a "HF Aggregator page" which brings together as many of the
on-line grabbers as possible onto a single page. Because of the
unpredictable nature of radio propagation we do
not promise you will see QRSS signals every time you view the grabbers
so its worth
checking back from time-to-time.
IK0VVE's "HF Aggregator" page.
What to look for.
As already indicated the greatest
QRSS activity will be found to be in the 30 Mtr band between 10.140000
10.140100 MHz. First
tune your receiver to 10.140 MHz (USB). Using a
stable test carrier or signal generator set to 10.140 MHz and loosely
coupled to the receiver antenna
the BFO/Clarifier control to give a "beat note" of around 800 Hz.. The
choice of 800 Hz for the beat
note is not critical, its just a fair bet that 800 Hz will be well
within the audio bandwidth limits of the receiver/sound card. If the
is set to low (say 250 Hz) it could be attenuated slightly by the
audio filtering, if the beat note is set to high (say 3000 Hz) then it
will fall outside of Argo's working window. At this point it is also a
good idea to check Argo's settings are the same as those in the image
below. For general QRSS viewing these settings have been found to be
optimal for most conditions and are recommended as a good starting
Now using Argo's "Full
for a continuous vertical line between 800 and 900 Hz, this
is your test signal. The appearance of a vertical line between 800 and
900 Hz assumes you have set your receiver to 10.140 MHz, checked the
calibration and also set the receivers audio beat note to 800 Hz. Now
position the mouse pointer on the vertical line and "click"
the left mouse button, this should then change Argo's display to a
horizontally scrolling window just over 100 Hz wide. After a few
minutes you should see a horizontal white line appear on the display
which corresponds to your test signal. How straight this line appears
depends on the stability of your receiver/test signal. Now switch off
signal and go back to Argo's "Full Band View" and look for
similar (though possibly weaker) vertical lines and again position the mouse pointer on
one of the vertical lines and "click"
the left mouse button to change Argo's display to the horizontally scrolling window.
a few minutes
you should have enough of the signal to look at to decide if it is a
QRSS signal or not. Do not be discouraged if you don't see
signals on your first attempts, a great deal depends on propagation,
current levels of QRSS activity, QRM levels etc.
Some examples of QRSS signals are shown below, they will give you an
idea of the sort of signals you might expect to see and the various
modes that are sometimes used. Various patterns are popular in QRSS
operation because they "stand out" better under poor conditions and the
patterns used are also a good way to "personalize" a QRSS transmission,
a sort of QRSS signature.
Click on any
of the thumbnails below to see a higher resolution image.
When to look.
WSPR (pronounced "whisper")
The WSPR (pronounced "whisper") capture
shown above is a recent development in the world of QRSS which
uses software running on a PC to generate a number of audio tones
with frequency spacing of only a few Hertz. These tones can be fed into
the microphone input of an SSB
transmitter in order to transmit a very narrow bandwidth (less than 10
Hz) coded signal.
While the coded signals can be viewed using Argo (or similar software)
the signals are intended for decoding using the WSPR software. The
coding of the signals conveys information such as call sign and
The software was written by Joe Taylor (K1JT) who also wrote the very
successful WSJT software used for meteor scatter experiments.
the time of writing (April 2008) the software is still developing with
many innovations and improvements still to come. A full description of this mode
is not possible because of the speed with which new developments to the
software keep appearing so for the latest information please go to Joe Taylor's WSPR download and
Link to WSPR download and
Most WSPR activity within the 30 Mtr band is (by voluntary agreement)
located in the 100 Hz segment directly above the10.140000
QRSS sub-band. So for WSPR activity look
10.140200 MHz though (at the time of writing) a number of stations are
operating outside of these limits due to the "congestion" on the band
from other WSPR operators, such is the popularity of this mode. A
number of operators are also using equipment with poor stability (by
QRSS standards) so they tend to "drift" outside of the agreed limits.
Also (at the time of writing) many of the WSPR operators are using far
to much power, WSPR is a very sensitive mode requiring very low power
(500 mW is normally enough) but many new WSPR operators who are also new to
QRSS are running several Watts! To be fair this can be due to the use
of commercial equipment which is not capable of power reduction below a
few Watts but the result of using to much power is to "swamp" the screens of QRSS viewers.
time to look is at
the week end when activity is normally at its highest. There is
sometimes activity during the week to but if you are new to QRSS and
looking for the
first time then the week end offers the greatest possibility of
success. The time to look depends on the the time of year, propagation
conditions etc so its a good idea to learn about the propagation
characteristics of the 30 Mtr band. I also recommend checking some of
the on-line resources mentioned towards the end of the "Where to look for QRSS"
section so you will know what the level of activity is likely to be.
QRM from contest stations (both CW and RTTY) can be a problem so try to
avoid those week ends when the contests are running. Though we share
the 30 Mtr band with other radio amateurs the QRM is normally not to
bad with the exception of contest week ends already mentioned. It is
not unusual for the odd CW or RTTY QSO to appear right in the middle of
the QRSS segment but generally (with the exception of contests) the
operators finish the QSO within minutes and move on. The slow nature of
QRSS means that over a period of a few hours several QRSS signals may
be copied with only sporadic interruptions by other band users. Most of
the time the other band users are unaware of the QRSS signals because
they are often sub-audible.
My own success at receiving QRSS was very slow to start with,
was partly due to my lack of experience with this mode and partly due
to the use of a receiver that had excessive frequency drift.
me several weeks before I saw my first confirmed QRSS signals.
Following my first successfully received QRSS signals the search
process became much quicker and easier, within a few more days finding
and capturing QRSS images became almost routine.
A QRSS sound sample.
find you are having difficulty in finding or tuning into QRSS signals
then perhaps the following 6 minute QRSS sound sample might help.
Because of local QRM at the time the recording was made you may find
that locating the QRSS signals is "challenging" but this recording
serves as a good example of what to expect in a "noisy" environment and
should provide a good signal to explore the features of Argo with. This
large "Zipped" Windows "wav" format file (4.57 M/bytes) which
can download, un-zip and then replay on your own P.C.
When you have successfully downloaded (using the link below) and
unzipped the file the next step is to select Argo's "Setup"
menu, then go into the "Select Input" menu followed by "Choose real
input" sub-menu. Now select the "What U hear" option and make sure all
other inputs to your P.C. sound card are disconnected. If you now play
the sound file you should be able to hear the sound playing in the
speakers of your P.C. while at the same time you should be able to view
the results in Argo as if it was "live" audio from your
Listening to the sound file you will hear a faint "buzzing" sound which
is the QRM from local T.V.'s and P.C.'s etc. You will also
hear some static from distant thunderstorms and if you have
exceptional hearing you may be able to hear the faint whistle of the
QRSS signals at around 1660 Hz, I cannot hear anything but QRM and
static but after processing with Argo the QRSS signals will be easily
detected and perfectly visible. To download the "Zipped" QRSS sound
sample click on the link below.
QRSS audio sample for downloading. Warning, large file (4.57
The sound sample was recorded on Monday the 23rd of October 2006 at
around 11:00 UTC using my QRSS 30 Mtr direct conversion
of the direct conversion receivers local oscillator offset the QRSS
band appears centered around 1660 Hz. If you select Argo's
"Full Band View" and look in the area of 1660 Hz you will see a couple
of unbroken vertical lines, they are the QRSS signals. You will also
see many more broken vertical lines which are of much greater
signal strength from around 400 to 1900 Hz. They are caused by local TV
QRM and my own P.C. monitors harmonics. Now
position the mouse pointer at a point corresponding to 1660 Hz and
the left mouse button, this should then change Argo's display to a
horizontally scrolling window just over 100 Hz wide. You should now have a
horizontal scrolling display which shows the QRSS band between 10.140000 to
just as I viewed it here at the time/date shown above. If you want the
horizontal display to show the correct frequency then enter the
following frequency offset (see Argo's instructions) of 10138385 into
Argo after which the horizontal window will then show the correct 30
Mtr band frequency plus or minus any small tolerance in the frequency
of your sound cards clock oscillator. You should be able to resolve two
FSK CW QRSS signals (plus QRM from TV/Computer etc), the FSK CW signal
uppermost (about 10.140080 MHz) is that of G4OEP, notice the
"spreading" of the signal probably due to multiple signals with some
Doppler shift. For me (here in the UK) this was a "short
skip" signal and happens quite frequently. The lower signal
10.140027 MHz) is that of DL6NL which is also an FSK CW signal and
remained visible for most of that day.
I played the audio clip a few hours after the recording was
to check it was valid and also took a screen capture of the recorded
signals using Argo,s screen capture feature. The captured image is
shown below and this is what you should see if you replay the audio
clip as described above.
information presented here is by no means exhaustive or complete but
hopefully it will give you some idea of the requirements for successful
QRSS reception. Based on my own experience it is possible to receive
QRSS signals with very modest equipment and worry about refinements
example, a receiver which has a modest amount of frequency drift will
often still produce good results if the user is willing to accept that
it may need constant re-tuning over a period of time. Such a receiver
only becomes problematic when you want to leave the system "capturing"
images automatically over extended periods. In such a case of
"unmanned" operation it may be found that the signals drift outside of
capture window and with no one around to correct the tuning some of the
signals may be missed.
I hope this has been helpful but if you still have unanswered questions
then please feel free to contact me and I will be happy to try and
questions relating to QRSS. Alternatively have a look at the "links"
section of this web site and also take a look at some of the other QRSS
"Knights" web sites,
this may help you to see the subject of QRSS from a
different perspective. If you decide that QRSS is for you then "welcome
aboard" and good luck with any QRSS projects you may undertake.
that’s about it, thank you for reading this and please
send any questions, comments or "heckles" etc to the e-mail address